ddllmcb

Greetings, For reasons not to be explained here, my 1996 targa sat in my garage for 2 years+ with the battery disconnected. Today, I took it to a CA smog test place for the smog check required to re-register the car. The smog test machine tested the emissions just fine, but was unable to obtain data from the onboard computers. The test machine screen read, "Not Complete" for several categories of required onboard computer information. The test operator, and a person at the CA DMV, told me that I must drive the car for 50+ miles, stop frequently during those 50 miles and turn off the ignition, start again, repeated 10 times or so, all the while turning the various electrical equipment on and off. I did this with no success. Now the operator advises starting the car cold with all electrical equipment turned on before ignition, then allow the car to idle for 30 minutes.

Sounds like voodoo. Can anyone educate me on the actual issue and how to get the car's computers into a state where the smog test equipment can read out what it needs? BTW, the car runs beautifully. Thx

blacksparrow

Try searching for "drive cycle", I'm sure others will chime in... here is one link

https://rennlist.com/forums/993-foru...e-a-champ.html

reefpix

I just did the "drive cycle" on my way to work and on the way home after getting my alternator changed (battery disconnected). Then I took it to the smog check place - it was all reset and it passed.

HTH
James

nine9six

Yep...Some OBDII readers (Actron CP9580) even monitor the drive cycle test, and will show when all cycles have been reset. At that point it is ready for smog testing.

Ed Hughes

Isn't the drive cycle on '96's indeed voodoo?

e3photo

The 96's seem to be a bit more difficult sometimes. My 97 has a 96 ECU (getting ready to replace with a new 97 one ) and I just got thru setting the flags after 2 complete drive cycles. :big gulp:


Emerald

tribaltech

Is this an issue on 95s? I disconnected my battery for the winter and will need to get an inspection sticker when I get the car out of hibernation. thx.

NYC993

I had this issue with my Toyota where i replaced battery and could not pass emissions due to their scanner not reading certain codes until i drove for 100+ miles to reset. The car was 2001 so OBD2.

Edit: i recall going back after driving for 30-50 miles and still failing, at which point the guy told me it may take 100-200 miles for it to reset. After a long trip i passed.

ddllmcb

Thanks for all the input. I have followed the guidance available here on rennlist, doing both versions twice and driving about 160 miles in the process. I went to two different smog test places, but showed 5 areas "Incomplete", which is no change from the first time.

One smog place suggested that I leave the car with them over night and they would find a "short" somewhere and solve the problem. I called the nearest Porsche dealer (150 miles away). They said they could solve the problem if I left the car with them for two days. When I asserted that that was not possible, they sent me the following. Seems to be intended for folks with specialized test equipment, but might help someone out there. In the mean time, my car has three year old tags and I still have no idea how to get it through smog. Thanks to all.
--------
From the dealer:

First bring the car up to operating temperature.
Turn on headlights and AC

Start car and use a stop watch
Do short test for evap and air injection
Hold RPM with throttle stick at 2K
At 4 minutes and 10 seconds, hold RPM at 4K for 90 seconds, let idle for 90 seconds
Reset engine to 2K
Go to cycle flag on the tester and wait fo rcat conv and oxy sensor aging to set
You will get 4 flag to set in about 20 minutes or less. After the four are set, let idle and wait for the FRA and TRA's to set
When all six flags are set, check in actual values that a trip has been registered. If not, drive the car until it has.

Repeat when the trip is set. After two trips the ready status should be set...

Lorenfb

"My 97 has a 96 ECU (getting ready to replace with a new 97 one ) and I just got thru setting the flags after 2 complete drive cycles."

Some '96 993s require three drive cycles (three trips with three cold starts).

"First bring the car up to operating temperature.
Turn on headlights and AC

Start car and use a stop watch
Do short test for evap and air injection
Hold RPM with throttle stick at 2K
At 4 minutes and 10 seconds, hold RPM at 4K for 90 seconds, let idle for 90 seconds
Reset engine to 2K
Go to cycle flag on the tester and wait fo rcat conv and oxy sensor aging to set
You will get 4 flag to set in about 20 minutes or less. After the four are set, let idle and wait for the FRA and TRA's to set
When all six flags are set, check in actual values that a trip has been registered. If not, drive the car until it has.

Repeat when the trip is set. After two trips the ready status should be set..."

The above is the procedure when using the Porsche factory testers, e.g. PST2.

OverBoosted28

Yeah, "leave the car with me for 2 days and come back". "Trust me" have you seen Ferris Bueller?

mdude

Must one complete a drive cycle after changing battery for MY 96 and higher 993s?

Lorenfb

"Must one complete a drive cycle after changing battery for MY 96 and higher 993s?"

A minimum of two is required.

pantdino

Nine9six, what color green is that?

David A

I don't think so since OBD 1 is simpler but someone here can confirm, I have a 95 too and I would like to know.